study material

1. Reproductive System

2. Function of the reproductive system
 Sexual reproduction requires a male and a female of the same
species to copulate and combine their genes in order to produce
a new individual who is genetically different from his parents .
 sexual reproduction relies on meiosis to shuffle the genes , so
that new combinations of genes occur in each generation ,
allowing some of the offspring of survive in the constantly –
changing environment .
 The male reproductive system produces , sustains , and delivers
sperm cells (spermatozoa) to the female reproductive tract .
 The female reproductive system produces , sustains , and allows
egg cells (oocytes ) to be fertilized by sperm . it also supports
the development of an offspring (gestation) and gives birth to a
new individual (parturition) .

3. Male Reproductive System
 Testis : Sex organ that produces sperm in a process called
spermatogenesis , and male sex hormones (testosterone).
 Developed in a male fetus near the kidneys , and descend to the
scrotum about 2 months before birth.
 Each testis is enclosed by a layer of fibrous connective tissue called
tunica alumina .
 Each testis contains about 250 functional units called lobules ; each
lobule contains about 4 seminiferous tubules where spermatogenesis
occurs .
 All somniferous tubules in a testis converge and form a channel called
rate testis .

4. Testis

5.  Scrotum: A pouch – like cutaneous extension that contains
the two testes . Located outside of pelvic cavity to prevent
overheating of testes [internal temperature of scrotum is
always about 3 ˚F below body temperature ] .
 Epididymis: An expanded tubule from the rate testis where
sperm is stored (for about 3 days) , matured and become
fully functional.Contains cilia on its columnar epithelium
that help move sperm toward vas deferens during
ejaculation. .
 Vas deferens: A tubule (about 10 inches long) that connects
epididymis to the urethra for transporting sperm during
ejaculation. Contains smooth muscle that undergoes rapid
peristalsis during ejaculation .

6. Accessory sex glands
 Seminal vesicles: secrete an alkaline solution that makes
up 60% of the semen volume ; this seminal fluid
contains fructose (nutrient for the sperm) and
prostaglandins (substances that stimulate uterine
contraction during sexual excitation).
 Prostate gland: secretes a slightly acidic , milky white
fluid that makes up about 30% of semen volume ; this
fluid helps neutralize the pH of semen and vaginal
secretion.
 Bulb urethral gland: secretes a clear lubricating fluid
that aids in sexual intercourse.

7. Reproductive organs of the male

8.  Urethra: A tubule located inside the penis for urine excretion and
semen ejaculation .Contains smooth muscle that performs rapid
peristalsis during ejaculation .
 Penis: A copulatory organ that is responsible for delivering the
sperm to the female reproductive tract. Contains 2 erectile tissues
called corpus cavernosa and corpus spongiosum , where the
latter one enlarges and forms the glans penis due to increased
blood flow during sexual excitation .
 During sexual excitement , parasympathetic nerves cause
vasodilatation in the penis , allowing erectile tissues to swell
and erect the penis .
 During ejaculation , sympathetic nerves cause vas deferens ,
urethra and erectile tissues to contract, forcefully expelling
semen (a mixture of sex gland fluids and about 300 million
sperm) outward .

9. Seminiferous Tubules
 About 1,000 seminiferous
tubules in each testis
conduct spermatogenesis.
 Between the tubules are
specialized glandular cells
called interstitial cells (or
leydig's cells ) which
produce testosterone.
 Inside the tubules are
specialized cells called
sertoli's cells which
support and nourish the
sperm.

10. Spermatogenesis
 Spermatogonia (containing 46 chromosomes) undergo DNA
replication and produce primary spermatocytes (with 46 pairs of
chromosomes) .[some spermatozoid undergo mitosis to maintain a
large population , so that spermatogenesis can be continuous for
many decades ].
 Primary spermatocytes undergo "crossing - over" to shuffle their
genes ,and undergo meiosis I which results in secondary sperm-
atocytes (each containing 46 unique chromosomes) .
 Secondary spermatocytes undergo meiosis II which produces
spermatids (with 23 unique chromosomes) .
 Spermatids now transform themselves into spermatozoa (also
containing 23 unique chromosomes) in a final event called
spermatogenesis .

11. Spermatogenesis

12.  Each spermatozoa consists of a head (which contains the 23
chromosomes), a mid piece (which stores mitochondria for energy
production) , and a tail. The head is enclosed by a structure called
acrosome which stores lays enzymes called acrosin for breaking
down the coatings surrounding the egg.

13. Journey of a Sperm
 at the end of spermatogenesis , spermatozoa are propelled by cilia in
the inner walls of rete testis toward the epididymes (the tails of these
sperm are not movable at this point) .
 inside the epididymis, certain enzymatic reactions occur that allow
spermatozoa to be fully matured and functional , but not yet have the
ability to fertilize the egg .
 if no ejaculation occurs during the 3- day storage time in the
epididymis , phagocytes will destroy millions of older sperm in
storage.
 during ejaculation , rapid peristalsis in the epididymis and vas deferens
propel the millions of sperm , passing the accessory sex glands ,and be
expelled through the urethra into the vagina of the female .

14.  after several minutes in the vagina (about 25% of sperm is
destroyed by the acidic secretion of vagina), the tail becomes
functional , propelling the sperm through the cervix and into the
uterus.
 half of the sperm will swim into the left uterine tube , while the
other half swim towards the right uterine tube . only one of the
uterine tubes carries the egg cell.
 sperm continue swimming toward the deeper end of uterine tube ,
against the expulsion force of the cilia lining the inner wall of
uterine tube .
 during this movement in the uterine tube, the acrosome is slowly
activated to prepare for the release of acrostin enzyme.

15.  by the time sperm has arrived at the ampoule region of uterine tube ,
only about 50 sperm are viable enough to try to fertilize the egg. And
usually only 1 sperm will penetrate through the coatings surrounding
the egg.
 each ejaculation emits about 2-6 ml of semen which contains about
300-400 million sperm . it takes the sperm about 2-12 hours to reach
the fertilization site in the uterine tube , but many sperm can survive
some where in the female reproductive tract for up to 2-3 days .
 one of the sperm will eventually penetrate through zone pellucida ,and
allow its cell membrane to fuse with the cell membrane of ovum . This
causes a rapid electrical depolarization at the cell membrane of ovum,
preventing other sperm entering the ovum (a phenomenon called poly
sperm ) .

16. Fertilization

17. The Human life Cycle

18. Mechanism of penile erection
 1. Sexual stimulation
 2. Parasympathetic neurons release nitric oxide,
causing dilation of small arterioles of penis
(meanwhile veins are compressed reducing blood
flow away from penis).
 3. Blood accumulates within the vascular spaces in
erectile tissue of penis .
 4. Penis swells & become erect .

19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Reproductive structure in the male

20. Mechanism of emission & Ejaculation ♂
 1. Intense sexual stimulation .
 2. Sympathetic impulses contract smooth muscles causing:
 Peristaltic contractions in testicular ducts, Epididymis, vas
deference and ejaculatory ducts .
 Rhythmic contraction in bulbourethral, prostate, and
seminal vesicles .
 Rhythmic contractions in erectile columns of penis .
 3. Emission-semen moves into urethra
 4. Ejaculation- semen is forcefully expelled from urethra .

21. Hormonal control of ♂ reproductive function
 1. Hypothalamic and pituitary hormones:
 The male body remains reproductively immature until the
hypothalamus releases GnRH (Ganadotropin – releasing
hormone), which stimulates the anterior pituitary gland to release
gonadotropins (FSH, LH) .
 FSH- stimulates spermatogenesis .
 LH (ICSH) – stimulates the interstitial cells to produce
male sex hormone (testosteronne) .
 Inhibin prevents over secretion of FSH . (Inhibin – from
substentacular cells of seminiferous tubules).

22. The brain – testicular axis

23. Male sex hormones
 2. Male sex hormones are called androgens .
 Testosterone is converted into dihydrotestestrone in some organs
(stimulates cells of these organs) .
 Androgens that fail to become fixed in tissues are metabolized in
the liver and excreted .
 Androgens production increases rapidly at puberty
 3. Action of testosterone :
 stimulates the development of the male reproductive organs and
causes the testes to descend .
 it is responsible for the development and maintenance of male
secondary sex characteristics (facial hair , deeper voice , muscular
development).

24. Regulation of male sex hormone
 a. Negative feedback mechanism regulates testosterone
conc.
 As the conc. of testosterone rises , the hypothalamus is
inhibited , and the Ant. pituitary secretion of
gonadotropins is reduced .
 As the conc. of testosterone falls , the hypothalamus
signals the ant. Pituitary to secrete gonadotropins .
 b. The conc. of testosterone remains relatively stable
from day to day.

25. Female reproductive system
ovary :
 primary sex organ that produces egg cells in a process called
oogenesis , and also produces female sex hormones such as
estrogens and progesterone.
 developed near the kidneys during fetal development ,and
toward the end of pregnancy descend into the pelvic cavity .
 consists of ovarian cortex where the ovarian cycle occurs ,
and ovarian medulla where scar tissues and connective tissue
are located .
 enclosed by a layer of cubical cells called germinal
epithelium.
 bound to the uterine tubes and uterus by ovarian ligaments .

26. Internal reproductive organs of a female

27. Structure of an ovary

28.  Uterine tube (or fallopian
tube): consists of firmbriae ,
finger – like appendages that
collect the ovum from the
ovary during ovulation.
 Infundibulum channels the
ovum from the firmbriae into
the uterine tube .
 Ampulla is the curvature of
the uterine tube where most
fertilization occurs .
 inner wall of uterine tube is
made of ciliated mucosa ,
where the cilia propel the
ovum toward the uterus .

29. Uterus
 a pear – shaped cavity formed by the union of the two uterine tubes .
 composed of 3 layers of tissue – perimetrium (fibrous connective
tissue) , myometrium (smooth muscle), and endometrium (epithelial
and connective tissues) .
 after fertilization , embryo adheres to the endometrial layer for further
development – an event called implantation .
 to prepare for implantation and development , endometrium is
stimulated by estrogens to thicken and becomes vascularzed – a
process called the menstrual cycle .
 myometrium ,under the stimulation of oxytocin, contracts during labor
to expel the fetus into the vagina .
 the base of uterus is closed by a narrow passageway called cervix to
prevent the entry of foregin substances

30.  Vagina: an elastic
channel inferior to the
cervix that serves as the
"birth canal" during
parturition.
 Also serves as the
copulatory receptacle ,
where it receives the
penis during sexual
intercourse.
 In addition to the acids
secretion from cervix , it
also coveys uterine
secretions (i.e. menstrual
flow).

31. Oogenesis
 In the ovarian cortex ,a process called oogenesis (formation of egg)
occurs to develop a mature ovum . Before birth , several million cells
called primordial oocytes exist in the ovaries – most of them
spontaneously degenerate .
 At birth , only 1 million primordial oocytes are left ; and by puberty
(age 10-11) ,only 400,000 remain in the ovaries .
 From puberty to menopause , some of these primordial oocytes
(containing 46 chromosomes) undergo DNA replication and become
primary oocytes (with 46 pairs of chromosomes ).
 Primary oocytes will then undergo "crossing - over" to shuffle their
genes, and meiosis I will occur to divide the cells into secondary
oocytes (containing 46 unique chromosomes) and the first polar
bodies (also containing 46 unique chromosomes ; but will be
degenerated) .

32. Events of oogenesis
 oogenesis now is arrested where
the ovary discharges a mature
secondary oocyte into the uterine
tube (in a process called
ovulation) .
 Meiosis II is reactivated when
this secondary oocyte is fertilized
by a sperm (if no fertilization
occurs , secondary oocyte is
discarded along with the
menstrual flow), instantly
dividing the 46 chromosomes into
23 (inside the second polar
body) and another 23 will be
united with the 23 chromosomes
released from the sperm.

33. Events of oogenesis

34. Mechanism of erection, lubrication, and orgasm in human female
 1. sexual stimulation .
 2. Arteries in the erectilc tissue dilate, vagina expands and elongates
 3. Engorged and swollen vagina increases friction from movement of
penis .
 4. parasympathetic nerves impulses from sacral portion of the spinal
nerve is enhanced .
 5. sexual stimulation intensifies .
 6. vestibule glands secrete mucus to lubricate .
 7. orgasm: rhythmic contraction of muscles of the perineum, muscular
walls of uterus, and uterine tube .

35. Hormonal control of ♀ reproductive function
 Hormones from the hypothalamus , Ant. Pituitary gland and ovaries,
play important roles in the control of sex cell maturation , and
development and maintenance of female secondary sex characteristics .
 Female sex hormones :
 A female body remains reproductively immature until about 10
years of age when gonadotropin secretion increases .
 The most important female sex hormones are estrogen and
progesterone.
 Estrogen is responsible for the development and maintenance of
most female secondary sex characteristics .
 Progesterone causes change in the uterus .

36. Hormonal control of ♀ secondary sex characteristic
 The hypothalamus releases GnRH , which stimulates the Ant.
Pituitary gland.
 The Ant. pituitary gland secretes FSH and LH .
 FSH stimulates the maturation of a follicle .
 Granulose cells of the follicle produce and secrete estrogen; LH
stimulated certain cells to secrete estrogen precursor molecules .
 Estrogen is responsible for the development and maintenance of
most female secondary sex characteristics .
 Concentrtion of Androgens affect other secondary sex
characteristics, including skeletal growth and growth of hair .
 Progesterone, secreted by the ovaries , affect cyclical changes in
the uterus and mammary glands .

37. Ovarian cycle
 A series of event in the ovarian cortex in order to produce a mature
ovum and sex hormones .
 Lasts for about 28 days , where from day 1 to 13 the mature ovum is
developed and estrogens are released ,on day 14 ovulation occurs to
discharge the ovum , and from day 15 to 28 scar tissues are formed and
progesterone is released .
 On day 1 , hypothalamus secretes Latinizing hormone releasing
hormone (LHRH) to the anterior pituitary gland , which in turn
secretes follicle – stimulating hormone (FSH) to the ovaries .
 Upon receiving FSH , about 20-25 primary follicles develop into
secondary follicles . [primary oocytes located inside primary follicles
undergo meiosis I and become secondary oocoytes , contained in
secondary follicles] .

38.  Follicular cells in secondary follicles begin to secrete estrogens (for
communicating with hypothalamus and anterior pituitary and for
developing the endometrium) .
 With continuous stimulation of FSH and some Latinizing hormone
(LH) ,secondary follicles continue to grow larger and develop multiple
layers of follicular cells (while the secondary oocytes within are
unchanged).
 By day 13 , only 1 secondary follicle will fully mature and become the
graafian follicle (or mature follicle) which secretes a large amount of
estrogens to the hypothalamus – anterior pituitary system for signaling
ovulation (using a positive feedback mechanism).
 On day 14 , large amounts of LH ("LH surge") will be secreted by
anterior pituitary , inducing ovulation where the graafian follicle
ruptures and releases the secondary oocyte into uterine tube .

39. Regulation of ovarian function

40.  From days 15 to 25 , graafian follicle degenerates and becomes corpus
hemorrhagicum ("a bleeding body") then corpus luteum ("a yellow
body"; containing lutein cells that secrete progesterone and some
estrogens to continuum stimulating the development of endometrium).
 By day 26 , if no fertilization occurs to the secondary oocyte, resulting
in a lack of human chorionic Gonadotropin hormone (HCG) from
the embryo , corpus luteum degenerates into corpus albicans . [if
fertilization did occur , HCG will continuously simulate corpus luteum
for 2-3 months , allowing high levels of estrogens and progesterone to
maintain pregnancy in the first trimester] .
 When corpus luteum degenerates , the declining levels of estrogens and
progesterone will signal the hypothalamus – anterior pituitary system
to initiate another ovarian cycle.

42. Menstrual cycle
 A series of events that occurs in the uterus in order to prepare the
endometrial layer for implantation and fetal development .
 Occurs simultaneously with the ovarian cycle , but is about 1 week
behind ; and also lasts about 28 days .
 From days 1 to 6 , the menstruation phase occurs where the top
portion of a thickened endometrial called stratum functionalis is shed
off from the previous cycle . tissue repair occurs to prepare for a new
menstrual cycle . Along with the stratum functionalist tissue , mucus ,
blood , and the secondary oocytes are discarded as "menses".
 From days 7 to 13 , increasing levels of estrogens from secondary and
mature follicles stimulate the endometrial to thicken and visualize – in
a stage called the preovulatory phase.

44.  From days 15 to 28 , continuous secretion of estrogens and
progesterone from corpus luteum causes the endometrium to
continue thickening and vascularizing – the postovulatory phase.
 Toward the end of this phase , if no fertilization occurs , resulting
in a lack of HCG stimulation to corpus luteum , the declining
levels of estrogens and progesterone will cause the endometrium
to degenerate – ultimately shedding off the stratum functionalis
layer .
 If fertilization did occur , high levels of estrogens and
progesterone from the corpus luteum (in the first trimester) and
from the placenta (in the second and third trimesters) will sustain
the thickness and vascularization of endometrium until the end of
pregnancy.

45. Major events in menstrual cycle - Summary
 1. The Ant. pituitary gland secretes FSH and LH .
 2. FSH stimulates maturation of a follicle .Granulose cells of the
follicle produce and secrete estrogen . Estrogen maintains 2ndry sex
traits & causes the uterine lining to thicken .
 3. The Ant. pituitary gland releases a surge of LH, which stimulates
ovulation . Follicular and thecal cells become corpus luteum cells
which secrete estrogen and progesterone.
 a. Estrogen continues to stimulate uterine wall development .
 b. Progesterone stimulates the uterine lining to become more
glandular and vascular .
 c. Estrogen and progesterone inhibit secretion of FSH and LH from
the Ant. pituitary gland .

46. The Menstrual Cycle

47.  4. If the egg is not fertilized , the corpus luteum degenerates and no
longer secretes estrogen and progesterone (24th day of the cycle).
 5.As the conc. of luteal hormones decline , blood vessels in the uterine
lining constrict .
 6. The uterine lining disintegrates and sloughs off, producing a
menstrual flow (28th day of the cycle).
 7.The Ant. pituitary gland , no longer inhibited, again secretes FSH and
LH .
 9. The menstrual cycle repeats .

49. Fertilization
 Within an hour after sexual intercourse , sperm would have traveled
from the vagina , through the cervix , into the uterus and uterine tube .
 during this journey , the acrosome on the head of spermatozoa would
be worn off , releasing acrosin enzyme by the time sperm are attached
to the outer coatings of the ovum .
 About 50 spermatozoa are attached to the outermost coating called
corona radiate . using hydrolysis reaction aided by acrosin , some of
these sperm reach the inner coating called zone pellucida .
 One of the sperm will eventually penetrate through zone pellucida, and
allow its cell membrane to fuse with the cell membrane of ovum . This
causes a rapid electrical depolarization at the cell membrane of ovum ,
preventing other sperm entering the ovum

50.  Now meiosis II is reactivated in the cytoplasm of ovum , dividing the
46 chromosomes in the nucleus into 23 chromosomes for fertilization
(uniting with another 23 chromosomes from the sperm) , and 23
chromosomes to be eliminated along with the second polar body .
 The head of the penetrated sperm is now detached from its mid piece
and tail . It will then rupture , releasing 23 chromosomes in the form of
long strands of DNA molecules .
 The chromosomes from the sperm and ovum now unite to form a
complete set of genetic makeup for the offspring – 2 haploid cells
(sperm and ovum) are now joined to become a single diploid celled
zygote . Fertilization is now complete .

52. Fertilization

53. Pregnancy
 1. A zygote is formed about 12-24 hours after ovulation .
 2. This single cell , still the same size as the original ovum , continues
to travel through the uterine tube toward the uterus by the action of
cilia along the inner lining of uterine tube .
 3. About an hour after fertilization is complete, mitotic cell division
called cleavage occurs , dividing the zygote into a cluster of smaller
cells .
 4. By the time cleavage has produced 16 identical cells , it is called a
morula (which occurs about 2-3 days after fertilization).
 5. Cleavage continues along the journey through the uterine tube , by
the time this cluster of cells has arrived at the uterus (abut 5-6 days
after fertilization) , it is called a blastocyst which contains hundreds of
small cells called blastomeres surrounding a hollow cavity called
blastocoel.

54. Cleavage from zygote to blastocyst

55.  6. The blastocyst releases digestive enzymes and embedds itself onto
the thickened and vascularized endometrium layer – a process called
implantation which occurs about 7 days after fertilization . The
blastocyst is now called an embryo, which continues to develop for the
next 2 months until a fetus is formed .

56.  7. Soon after implantation , layers of membrane begin to form outside
the embryo –
 a. Chorion – the innermost membrane which secretes a hormone
called the Human Chorionic Gonadotropin (HCG) which
stimulates the corpus luteum in the ovary for the secretion of
estrogens and progesterone , until the placenta is fully developed
and can secrete estrogens and progesterone.
 b. Amnion – the middle membrane that secretes amniotic fluid
for nourishing the embryo.
 c. Placenta – the outermost membrane that protects the embryo
and fetus, allows exchange of nutrients and wastes between fetal
and maternal blood, and secretes estrogens and progesterone to
maintain pregnancy .

57. The placenta

58.  8. In the first 3 months of pregnancy (or "first trimester") , HCG
level is the highest and it declines in the last two trimesters. This is
to ensure that corpus luteum is sustained and not degenerated into
corpus albicans . [HCG is secreted by renal tubules into urine ,
allowing pregnancy to be tested positive in a typical pregnancy test .
the high HCG level may be responsible for "morning sickness " and
other discomfort felt by pregnant women].
 9. In the last two trimesters , placental estrogens and progesterone
cause the uterus and breasts to enlarge , and during labor, cause the
vagina to stretch. The sharp decline of estrogens after birth will
signal new ovarian and menstrual cycles to begin. The sudden
reduction of progesterone before birth removes the suppression of
oxytocin (from posterior pituitary gland), resulting in uterine
contractions during the birth process.

59.  10. pregnancy lasts for about 40 weeks (280 days after the last
menstruation or 266 days after fertilization) and ends with partuition.
 a. During the last 6 weeks of fetal development , the fetus assumes the
vertex position where the head faces the cervix .
 b. At the end of pregnancy , the fetus moves downward and its head
causes pressure onto the dilating cervix , [the hormone Relaxin from
the ovaries stimulates the dilation of cervix and pubic symphysis].
 c. The pressure onto the cervix signals the hypothalamus which in turn
stimulates the posterior pituitary gland for the release of oxytocin.
 d. Oxytocin causes the myometrium layer (made of smooth muscle) to
contract involuntarily , pushing the fetus downward .
 e. The downward movement of fetus exerts more pressure onto the
cervix , a phenomenon called positive feedback – until the fetus is
expelled from the uterus, through the cervix and vagina , to the outside.

61. Hormonal changes during pregnancy - summary
 1. Following implantation , cells of the trophoblast (embryonic cells
that helps from the placenta). begins to secrete HCG (human chorionic
gonadotropin) .
 2. HCG maintains the corpus luteum, which continues secreting
estrogen & progesterone .
 3. As the placenta develops, it secrets large quantities of estrogen and
progesterone. placental estrogen and progesterone :
 a. stimulate the uterine lining to continue development .
 b. maintain the uterine lining .
 c. Inhibit secretion of FSH and LH from the Ant. pituitary gland .
 d. stimulates development of the mammary gland.

62.  e. Inhibit uterine contractions (progesterone) .
 f. enlarge the reproductive organs (estrogen) .
 4. Relaxin from the corpus luteum also inhibits uterine contractions
and relaxes the pelvic ligaments .
 5. The placenta secretes placental lactogen that stimulates breast
development .
 6. Aldosterone from adrenal cortex promotes reabsorption of sodium
(leading to fluid retention).
 7. Parathyroid hormone from the parathyroid glands helps maintain a
high conc. of maternal blood Ca++ (due to high fetal demand for
calcium).
 Note : Detecting HCG in a woman’s urine or blood is used to confirm
pregnancy .

63. Factors contributing to labor process
 1. As the time of birth approaches, secretion of progesterone declines,
and its inhibiting effect on uterine contractions may lessen .
 2. Decreasing progesterone conc. may stimulate synthesis of
prostaglandins, which may initiate labor .
 3. Stretching uterine tissues stimulates release of oxytocin from the
post. Pituitary gland .
 4.Oxytocin may stimulate uterine contractions and aid labor in its later
stages .
 5. As the fetal head stretches the cervix, a positive feedback
mechanism results in stronger and stronger uterine contractions and a
greater release of oxytocin .

64.  6. positive feedback stimulates abdominal wall muscles to contract
with greater and greater force .
 7. The fetus is forced out through the birth canal to the outside.

65. Hormonal control of mammary glands
 I. Before pregnancy (Beginning of puberty) :
 Ovarian hormones secreted during menstrual cycles stimulate
alveolar glands and ducts of mammary glands to develop.
 II. During pregnancy :
 Estrogen causes the ductile system to grow and branch.
 Progesterone stimulates development of alveolar glands
 Placental Lactogen promotes development of the breasts .
 Prolactin (from Ant. pituitary) is secreted throughout pregnancy
, but placental progesterone inhibits milk production (until after
birth).

66. Structure of lactating mammary glands

67.  III. Following childbirth :
 Placental hormonal
concentrations decline , so
that the action of prolatin is
no longer inhibited andthe
breasts begin producing milk.
 Mechanical stimulation of the
breasts releases oxytocin from
Ant. pituitary gland.
 Oxytocin stimulates ejection
of milk from ducts.
 As long as milk is removed ,
more prolactin is released ; if
milk is not removed , milk
production ceases.

68. Birth Control
 1.Birth control is a voluntary regulation of conception.
 2. Contraception is any method used in birth control to prevent
fertilization of the ovum.
 3. The most common contraceptive methods and their success rate –
 a. Abstinence (100%) done by male and female where sexual
intercourse is avoided.
 b)Vasectomy (99%) done by male where the vas deferens tubes are cut
to prevent sperm transport.
 c) Tubule ligation (99%) done by female where the uterine tubes are
tied or cut to prevent ovum transport and passage of sperm.
 d) Birth control pills (98%) taken by female in which daily moderate
level of estrogens suppress the ovarian and menstrual cycles.

69.  e) intrauterine devices (IUDS) (95%) inserted under the cervix in
female activates leukocytes and antibodies to be formed in the female
reproductive tract , preventing sperm from entering the uterine tubes .
 f) condom (90%) used by male or female is impermeable to sperm
during ejaculation . [condoms also could prevent the transmission of
sexually transmitted diseases] .
 g) diaphragm and / or foam (80%) used by female block the entrance
of sperm into the cervix .
 h) withdrawal method (or coitus interrupts) (75%) done by male in
which the penis is withdrawn from the vagina before ejaculation
occurs.
 i) Rhythm method (75%) done by female where sexual intercourse is
performed only before ovulation and about a week after ovulation
occurs , there are three ways to time ovulation.

70. Sexually transmitted diseases (STDs)
 1. formerly called venereal diseases (VDs).
 2.bacterial or viral infections that are spread through sexual contact .
 3. Gonorrhea
 Caused by bacterium named Neisseria gonorrhoeae. Bacteria
invade the mucosal layer of reproductive and urinary tracts.
 Most common symptoms in male is urethritis (infection of
urethra), resulting in painful urination .
 Symptoms in female include abdominal discomfort , vaginal
discharge ,and uterine bleeding .
 Penicillin and tetracycline antibiotic drugs are effective ,but
sometimes bacteria might be resistant to these drugs.

71.  4. Syphilis
 a) caused by a bacterium named Treponema pallidum . It can be
transmitted from mother to fetus where the fetus usually will be
stillborn or die after birth .
 b) bacteria penetrate mucosal layer and skin easily ,and enter into
blood and lymph .
 c) incubation period is about 12 weeks, after which a red , painless
lesion appears on external genitalia .
 d) if untreated , pink skin rash will appear all over the body. Fever ,
joint pain , anemia , hair loss will occur if still untreated .
 e)final stage of development occurs after a 10-years latent period –
bacteria invade central nervous system , blood vessels , bones , skin ,
and other organs – which might lead to death . penicillin is the only
known treatment , but only effective during early stages of symptoms .

72.  5. Chlamydia
 Caused by a bacterium named Chlamydia trachomatis.
 The most common STD in U.S.
 Infects 3-4 million new victims each year .
 Responsible for 25-50% of all pelvic inflammation .
 Each year about 150,000 infants are born with the disease (in these
cases , Chlamydia becomes a "congenital disease " where the fetus
acquires the bacteria from mother's vagina during the birth process).
 Symptoms are often unrecognized – urethritis , vaginal discharge ,
abdominal pain , painful urination and intercourse ,and irregular
menstruation .
 Infants tend to develop pneumonia .
 Treatment is tetracycline .

73.  6. Genital herpes
 a. caused by a virus named Epstein – Barr Virus (EBV) .
 b. the most difficult STD to control or treat .
 c. most common type of genital herpes is herpes simplex virus type
II (which affects mainly the lower body) .
 d.symptom is usually painful lesions on reproductive organs .
 e. can cause severe malformation of a fetus .
 f. can remain latent for years in the body with no signs or
symptoms .
 g. about 25-50% of all Americans might carry this virus .